Thanks to the Helicycle

[dcnblues]

I'm a 48 year old broke writer, but I've been flying in anything I could bum a ride in since I was a kid. Got my single engine land pilot's license when I was at UCSB, but haven't ever really had the money to build, own, or even rent aircraft. I got a hang glider certification (only Hang II), did some skydiving, but have never ridden in a helicopter (still).

The internet and a few friends keep me interested in flying, but I'd never really been interested in rotorcraft. Up until about a decade ago, I wasn't even clear that helo's could autorotate. That was a big piece of news.

At the Golden West fly in a few months back I saw a couple of sleek kit turbine helos (yes, Helicycles), and kept coming back to them. I've forgotten the name of the nice gentleman who answered questions for well over an hour, but I really pestered him as every part of the kit was just cooler than hell, and I wanted to understand how each part worked.

I joined this forum, and have been reading up on all kinds of cool (and new to me) new tech. Anyway, I just wanted to thank you guys for your cool toy which I seriously envy. And which got me temporarily obsessed with rotorcraft.

One thing is that I've gotten interested in autogyros, and am curious about comparing them to your thirsty turbine. I remember a figure of 12 gph (diesel). Can you tell me more about fuel burn in the Helicycle?

What's the rate at 80mph?
What's the standard power setting for cruise in a turbine? 75%? I know zip about turbines.
Standard cruise speed for Helicycle?
What speed gives best range / compromise?

Many thanks - Ian

 

[bryancobb]

Welcome Ian,

You were not hallucinating! The Helicycle does burn 12 or 13 per hour in a hover and at 100MPH. Slightly less if slower but it IS very thirsty! Probably 7 or 8 gals at 80MPH.

Two-Stroke Mosquitoes and gyros get down into the 4 or 5 gallon range but the 2-strokes are a little finnicky and require more knowledge and attention to detail.

 

[StanFoster]

Ian- I see you got bit by the same bug that bit me. I bet you were talking to Hap Miller at that fly-in. Fuel burn.......yep they are thirsty. Mine burns 13 gallons per hour going 100 or hovering. No way will it burn much less than 11 gallons at mprs. 7 or 8 gallons? I wish! However, the fact that you have such a dependable powerplant, no cooling system to maintain, and just an abundance of power, it has been the best experience I have ever had with an aircraft. I would have never bought one if it had a screaming 2-stroke in it. Too borderline being on the edge of having enough power with my big butt, except with the turbine. Mine loves to cruise between 100-105 mph...and that is actual airspeed. Most of my flying is around 70 mph when I am just flying around in no hurry getting anywhere. Best range is a good question. I know my max fuel burn increases as I go faster past mprs-minimum power required speed, but I really can't see much difference in total fuel burn if I am cruising somwhere 70 or going 1.5 times faster at 105 mph. I flew to mentone right at 100 mph and saw right at 12.5 gallons per hour. I normally average closer to 13 gallons per hour before my streamlining was done. Stan

 

[dcnblues]

And they're not as cool as the turbine.

If I had a helicycle it would be hard not to paint it in combat camo, and put some kind of external camera mount on it that made it look weaponized.

It's one seriously cool / evil / sleek looking machine. I loved everything about it. :whoo:

 

[dcnblues]

... Best range is a good question. I know my max fuel burn increases as I go faster past mprs-minimum power required speed, but I really can't see much difference in total fuel burn if I am cruising somwhere 70 or going 1.5 times faster at 105 mph. I flew to mentone right at 100 mph and saw right at 12.5 gallons per hour. I normally average closer to 13 gallons per hour before my streamlining was done. Stan

Thanks Stan. Briefly, because I don't remember, where's the air intake on the helicycle? Do you get increased engine efficiency with increased speed, as turbine fixed wings do?

 

[bryancobb]

Wow! it's thirstier in cruise than I THOUGHT it would be.

 

[StanFoster]

Ian- The air intake is a cylindrical mesh screen just in front of the compressor wheel. It has 1/8 inch squares,and that is your air filter also. A turbine still amazes me how few parts they have, and the rpm's they turn. Stan

 

[baronpilot]

It burns 13-14 GPH point to point x-country. Arguably the best engine available in a single place helicopter. When someone makes the DI Rotax 800 work in a machine it will be the best burning about 6-7 GPH and rebuildable for less than $1500 with an unlimited supply of parts.

 

[baronpilot]

Ian- The air intake is a cylindrical mesh screen just in front of the compressor wheel. It has 1/8 inch squares,and that is your air filter also. A turbine still amazes me how few parts they have, and the rpm's they turn. Stan

Stan is correct. This is a simple design, but we have to be careful when we talk about a "turbine" and it's parts. While the Solar has a "turbine" wheel it is really just a centrifical compressor that sucks in the air through the screen he noted and then compresses that air using centrifical force against the wall. This is a single rotor system with one side being the intake and the other being the combustion side. Very simple and cheap to make and very reliable in all ground operations it was intened for.

Now, for aircraft it is also very reliable, but it is the least efficient engine you can install and it has other issues a "real" turbine does not.

First, let's talk about efficiency. It burns about 1.3 lbs of Jet Fuel per HP per hour. So, if you are using an average of 75 HP you will burn roughly 14 GPH. Now, let's talk about the Allison C18 in an efficiency comparison. It will make up to 317HP and weighs the same as the Solar. The difference is in how it makes power. Instead of using centrifical force like a turbo in your car or the Solar, it uses airflow induced radially though multiple power and compression stages. This airflow is much more efficient and yields a fuel burn of 0.7 lbs per HP per hour. So, even though it will make 317 HP, using 75 HP it still only burns 7.7 GPH. This is almost 100% more efficient.

Now, let's talk about the other advantages. Here is the big one in my opinion. In a free turbine like the C18 you can hard mount the engine and start the helicopter without trying to engineer some crazy clutch that will allow for a startup with no load and then slowly apply load when you need it. With the free turbine there is no mechanical interconnect (just air) between the power turbine wheels and the compressor wheels, so you simply start the engine and the air flow slowly begins turning the rotors as the free turbine is being forced to turn by airflow. This is much more reliable than a clutch and has zero maintenance. Next, the C18 uses a mechanical fuel controller that is built like a tank. It fails almost never. In fact, the C18 engine has a failure rate of 1 in 120 years of actual operation. There is no more reliable engine and it's low RPM droop recovery is far superior than a single stage turbine.

Now, let's get back to parts. The Solar is a single stage turbine and therefore is as simple as parts get. Basically just one rotor, one bearing, some fuel injectors, fuel controller, and governor. Yes, that is simple and cheap and that is why it is in the Helicycle. That single bearing can also be a problem. There have been quite a few Helicycles that have needed the bearing replaced back there (mine needs it now) with many of them experiencing the rotor rubbing the walls. The engine was built to run a generator on the ground at 1G, so you want to fly modestly. A used C18 would add another $30k to the cost of the Helicycle and most would find that cost prohibitive. Then again, there are people like me that want the most reliable/efficient engine they can get. A C18 might make sense considering that in 1000 hours of flight time it will save you 7000 gallons of fuel @ $5 per gallon = $35,000. The added reliability of the C18 along with the ability to get rid of a poorly designed clutch might just be worth it. I am considering it for my Helicycle. The T62 might find it's place in a golf cart instead.

 

[StanFoster]

The one HUGE advantage that the T-62 has made for me is the simple fact that this is the only turbine engine I could ever afford. My flying experience would have been totally void of having my own helicopter had the T-62 turbine powered Helicycle not ever came along. There just simply is not another helicopter out there that I could afford to buy that would haul my butt with abundance of power. I still would have been flying my SparrowHawk........ I am much more optimistic about this turbine than what was just stated, but that is based on many dozens of pilots that are accumulating lots of hours, including myself. The fleet total now is around 6000 hours. My Helicycle has so far required MUCH less maintenance than any of the four other gyros I owned and flew. Stan

 

[bryancobb]

Todd,

There is absolutely no doubt that a multi-stage free turbine is better suited for a helicopter. Their cost is just astronomical. If you can get an Allison C-18 for $30k and you plan on flying your Helicycle for 1000 hours or more, I'd go for it.

There's a little efficiency lost in-between the compressor spool and power turbine because that connection isn't 100% locked together like a car's torque converter does at RPM. Still it's way better than 14 gallons per hour. The compressor spool is supported by more than one bearing that are separated by a significant distance which makes it very tolerable to changing g's from all directions without making the gyroscopic forces put crazy pressures on the bearings.

The T-62 is a sweeet little engine for the Helicycle, but it is thirsty as I said earlier in this thread. The fact that it acts as the clutch is not the best Idea I have seen. The engine should be stationary in the frame, with pulleys aligned, and the idler should be moved to tighten the belts, not the engine, but then who am I to know??

 

[baronpilot]

Bryan. I agree 100%. The C18 in the JT 300 is burning less than 11GPH. No clutch and no problems. $30k buys you an excellent serviceable C18 and running it at 40% or less of its rated power makes it last forever.

Like I said, the Solar works fine, but the clutch is severely lacking. In the long run, the C18 would be better.

 

[9aplus]

How about this one?

http://www.pbsvb.com/turboprop-engine-tp-100-and-turboshaft-engine-ts-100

http://www.pbsvb.com/pdf/dlt_motor_tps100/en_tps100.pdf

 

[dcnblues]

Dammit Baron, I have only have room in my head for so many obsessions at a time! I'm new to rotorcraft, as I said, and was busy trying to really grasp, in my head, hub design and swashplate pivot bearings. Without holding a swashplate in my hand, I'm still having a hard time modeling / seeing it (and imagining the rotational speeds, stress, friction requirements, etc).

Then you go and give me fascinating details about even better engines! I had looked up the T-62 and thought re-purposing it for a helo was pretty cool, but now you had to go feeding the 'what if' part of my brain stem.

It is good to learn everything, and to be familiar with the inevitable limitations inherent in anything mechanical and cool. Thanks for all the expert posts.

Will a C-18 run on diesel?
How much do you think that TP 100 will cost? Will you be able to get it in a non-certified version?

 

[bryancobb]

Deacon,

They told us in flight school that these turbines will RUN ON ANYTHING!!! The T53-L-13 in the Huey even listed NORMAL GASOLINE as an alternate fuel!!! It just had to have some maintenance done on it after.

Kerosene, Diesel, JP-4, JP-5, Mineral Spirits, MoGas, - - - - - - >